Wind effects on surface to bottom fronts

Abstract

In nearshore regions, water of reduced density is frequently present owing to freshwater influx or spring heating. Under some circumstances, light nearshore water is confined to one side of a density front, extending from surface to bottom, and is called ‘spring thermocline’ or ‘shelf edge front.’ The shape and permanency of this front are affected by wind stress, which may interfere with the momentum balance in a direction parallel to the front and cause geostrophic adjustment motions normal to the front. A simple geostrophic adjustment theory elucidates some of the more important effects of wind on such fronts. Winds opposing the geostrophic flow above the inclined front tend to flatten its shape and eventually destroy the front, sometimes causing the formation of a surface ‘lens’ or ‘bubble.’ Comparison with observations from Lake Ontario and from the New England continental shelves shows that the theory gives a realistic first‐order description of frontal behavior.